The effect of wear phenomena of grinding wheels with sol-gel alumina on chip formation during internal cylindrical plunge grinding of 100Cr6 steel

Abstract

The article presents the results of experimental investigations to determine the effect of wear phenomena of grinding wheels with sol-gel alumina abrasive grains on chip formation during internal cylindrical plunge grinding of 100Cr6 steel. Basic wear phenomena conducted during the grinding process using microcrystalline sintered corundum abrasives are described. In order to expand our knowledge of this phenomena, experimental tests were conducted in two stages. In stage 1, only one opening was machined, which corresponded to the removal of 464 mm3 of workpiece material. In the second stage, the process was carried to machine 100 subsequent openings (material removal Vw = 46,400 mm3). Such methodology allowed one to observe changes in the form of chips resulting from the progressive wear of the grinding wheel components. The form and size of the chips were identified by recording and analyzing the SEM micrographs of the chips for both grinding stages, respectively. Conducted studies have shown that the dominant type of chips, shaped in the initial period of the grinding wheel’s life, are large (several hundred μm in length) flowing-type chips resulting from material removal by sharp cutting edges of abrasive grain active vertices. At the end of the grinding wheel’s life, when active vertices of abrasive grains have clear signs of large fatigue and thermo-fatigue wear, only in the near-edge zones of the wheel can flowing-type and shearing-type chips (usually less than 100 μm in length) be observed, while knife-type and slice-type microchips were predominately registered on the whole grinding wheel surface.